Packages allowing significant penetration of oxygen or other gases are undesirable where gas transmission contributes to the decay of the packaged product. For example, the development of packages having low oxygen transmission rates, i.e. high oxygen barrier properties, has long been a desirable objective in the food packaging industry, because low gas permeability food packages increase the shelf life of the packaged food products. Packages having low oxygen transmission rates also have utility for packaging other oxygen sensitive materials, such as oxygen activated sealants. Longer shelf life of the product increases inventory efficiency for distributors, and reduces the likelihood that the consumer will accidently purchase a contaminated product. For a plastic film no be qualified for food packaging applications, therefore, the film has to have low oxygen permeability not only at flow relative humidity, but also at high relative humidity since the packed food may be stored in the high humidity environment. Unfortunately most of the commercially available plastic film cannot meet these two requirements simultaneously. For example, polyvinylalcohol has very low oxygen permeability at 0% relative humidity but high oxygen permeability when the relative humidity exceeds 70%. On the other hand, the oxygen permeability of polyolefins such as polyethylene and polypropylene are independent of relative humidity, but have oxygen permeability which is too high for food packaging applications. The ideal film will have both low oxygen permeability and will be insensitive to relative humidity. The present invention solves these problems by teaching a multi-layer composite, silicone treated plastic film which exhibits excellent low gas transmission characteristics both at 0% relative humidity and at 85% relative humidity. The resulting films are transparent, flexible and creasable, and will not crack when bent.